1. Field of the Invention
This invention relates to magnus rotors and more specifically to the use of magnus rotors as part of a system for generating electricity from wind energy.
2. Description of the Prior Art
It is generally accepted that a magnus rotor can only be revolved at about four times the wind speed for the purpose of converting wind energy into electrical energy. Experiments have shown this to be correct with the present technology. This is because as the magnus rotor is made to spin faster and faster the aerodynamic drag is built up rather rapidly to the point where it takes more energy to revolve the rotor than the energy output of the system. Referring to U.S. Pat. No. 4,582,013 and the research upon which it is based as expressed in U.S. Dept. of Energy Grant Report #DOE/R6/10969 we see various attempts to reduce aerodynamic drag. In FIG. 6 and others of the U.S. Pat. No. 4,582,013 we see the addition of a tail which is swung by the wind. This reduces drag downwind from the rotor. In the Grant Report there is described a “Circulator” to reduce induced drag. See page 16 of the report.
When the rotor is made to rotate, the top and bottom plates of the rotor also rotate and cause the air next to them to swirl, causing aerodynamic drag to be induced. The design of the “Circulator” imposes a mechanical barrier to prevent this circulation.
Also worth mentioning is the statement in U.S. Pat. No. 4,582,013 column 28, lines 33-35 “Wind tunnel tests show major improvements in aerodynamic performance due to the presence of shield 9, and due to aerodynamic seals.” The structure of this shield is explained in col. 28, lines 28-32.